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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
        <div>
                <input type="checkbox" name="aa" value="0" />0
                <input type="checkbox" name=" aa " value="1" />1
                <input type="checkbox" name=" aa " value="2" />2
                <input type="checkbox" name=" aa " value="3" />3
                <input type="button" onclick="abc()" value="提 交" />
                <div id="allselect"></div>
            </div>
            <div>
                    <form name="a">
                        <select name="a" size="1" onchange="_sel(this)">
                        <option value="a">1</option>
                        <option value="b">2</option>
                        <option value="c">3</option>
                        </select>
                    </form>
                </div>   
                <div>
                        用户名：<input type="text" id="username"/><br/>
                        密  码：<input type="password" id="password"/><br/>
                    　　 确认密码：<input type="password" id="password1"/><br/>
                        <button id="btnSubmit" type="button">提交</button><br/>
                    </div>   
                    <table>
                            <tr>
                                <td>留言</td>
                                <td id="number"> 0 </td>
                            </tr>
                            <tr>
                                <td colspan=2>
                                    <textarea id="feedBack" onkeyup="test()" rows=6></textarea>
                                </td>
                            </tr>
                        </table>                
    <script src="./js/jquery-3.6.0.js"></script>
    <script src="./js/base.js"></script>
</body>
</html>